[Utilization of oxygen radicals by synthetic proline-rich oligopeptides].

Inhibition of superoxide by two synthetic proline-rich hexapeptides simulating the hinge region of the IgG molecule has been studied. The CPPPEL (P-Cys) peptide was active in utilizing superoxide (O2.-), while the APPPEL (P-Ala) peptide had no such activity. Spontaneous formation of clusters with six and/or eight monomers was shown for P-Cys, but not P-Ala. Preincubation of mixed P-Cys and P-Ala resulted in the appearance of a product with a high affinity for O2.-. Incubation of the mixture at 56 degrees C led to inactivation. Preincubation of P-Cys with ZnCl2 reversed the main pathway of O2.- utilization by P-Cys. The relationship of the P-Cys activity to its clusterization is discussed.